Buy Gefticip 250 mg Iressa (Gefitinib) is used in the treatment of lung cancer. It helps to treat non-small-cell lung cancer by blocking the action of an enzyme known as tyro sine kinase. This enzyme is believed to be needed by the cancer cells to multiply, so by interfering with its function the medication helps to prevent the growth of cancer cells and slow down their ability to spread throughout the lungs and beyond.